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Abstract:

An integrated circuit can include first and second FETs of a particular
conductivity type on a substrate, wherein a first source/drain region of
the first FET is closer to a center of a first channel region of the
first FET than a second source/drain region of the second FET is to a
center of a second channel region of the second FET.

Claims:

1. An integrated circuit comprising: first and second FETs of a
particular conductivity type on a substrate, wherein a first source/drain
region of the first FET is closer to a center of a first channel region
of the first FET than a second source/drain region of the second FET is
to a center of a second channel region of the second FET.

2. The circuit of claim 1 wherein a first interface of the first
source/drain region and the first channel region is closer to the center
of the first channel region than a second interface of the second
source/drain region and the second channel region is to the center of the
second channel region.

3. The circuit of claim 1 wherein the first and second source/drain
regions comprise a particular lattice constant, and wherein the first
source/drain region applies greater stress to the first channel region
than the second source/drain region applies to the second channel region.

4. The circuit of claim 3 wherein the first source/drain region extends
past an outermost lower corner of a gate structure of the first FET into
the first channel region to define an undercut region beneath the first
FET; and wherein the second source/drain region is aligned to a gate
structure of the second FET.

5. The circuit of claim 1 wherein the first and second source/drain
regions comprise first and second raised source/drain regions,
respectively, wherein the first source/drain region extends past an
outermost lower corner of a gate structure of the first FET into the
first channel region to define a first undercut region beneath the first
FET; and wherein the second source/drain region extends past an outermost
lower corner of a gate structure of the second FET into the second
channel region to define a second undercut region beneath the second FET.

6. The circuit of claim 1 wherein the first and second source/drain
regions comprise different lattice constants than the first and second
channel regions.

7. The circuit of claim 1 wherein the first and second source/drain
regions comprise first and second raised source/drain regions,
respectively, wherein the first raised source/drain region wraps around
an outermost lower corner of a gate structure of the first FET into the
first channel region to define an undercut region beneath the first FET;
and wherein the second source/drain region is formed aligned to a gate
structure of the second FET.

8. The circuit of claim 1 wherein the first and second source/drain
regions comprise first and second raised source/drain regions,
respectively, wherein the first raised source/drain region wraps around
an outermost lower corner of a gate structure of the first FET into the
first channel region to define a first undercut region beneath the first
FET; and wherein the second raised source/drain region wraps around an
outermost lower corner of a gate structure of the second FET into the
second channel region to define a second undercut region beneath the
second FET.

9. The circuit of claim 1 further comprising: a first spacer including an
outer side wall of a gate structure of the first FET to provide a first
thickness; and a second spacer including an outer side wall of a gate
structure of the second FET to provide a second thickness that is greater
than the first thickness.

10. The circuit of claim 9 wherein the first source/drain region is
formed self-aligned to the first spacer and the second source/drain
region is formed self-aligned to the second spacer.

11. The circuit of claim 9 wherein a number of layers included in the
first spacer is less than a number of layers included in the second
spacer.

12. The circuit of claim 11 wherein the first source/drain region is
formed self-aligned to the first spacer and the second source/drain
region is formed self-aligned to the second spacer.

13. The circuit of claim 1 wherein the first and second FETs comprise
PMOS FETs, the first and second channel regions include a first material
comprising a first lattice constant and the first and second source/drain
regions include a second material comprising a second lattice constant
that is greater than the first lattice constant.

14. The circuit of claim 13 wherein the first material comprises Si and
the second material comprises SiGe.

15. The circuit of claim 1 wherein the first and second FETs comprise
NMOS FETs, the channel regions include a first material comprising a
first lattice constant and the source/drain regions of the first and
second FETs include a second material comprising a second lattice
constant that is less than the first lattice constant.

16. The circuit of claim 15 wherein the first material comprises Si and
the second material comprises SiC.

17. The circuit of claim 1 wherein the first and second source/drain
regions are both recessed below a surface of the substrate.

18. The circuit of claim 1 wherein the first and second channel regions
comprise a respective fins that extend from the substrate to protrude
from a device isolation layer to provide upper side walls and a top
surface of the respective fins positioned between the first and second
source/drain regions, respectively.

19. The circuit of claim 18 wherein at least one of the respective fins
comprises a width measured between the upper side walls of about 20 nm or
less.

20. The circuit of claim 19 wherein the at least one of the respective
fins comprises a side wall image transfer fin.

21. The circuit of claim 1 further comprising: first and second gate
electrode structures included in the first and second FETs, respectively,
wherein the first and second gate electrode structures each include a
first conductive gate layer in an outer portion of the respective gate
electrode structure and a second conductive gate layer in an inner
portion of the respective gate electrode structure, in a recess defined
by the first conductive gate layer.

22. The circuit of claim 21 wherein the first and second conductive gate
layers comprise first and second metal layers, respectively.

24. The circuit of claim 1 wherein the substrate comprises bulk silicon
or a silicon-on-insulator substrate.

25. An integrated circuit comprising: a substrate; a first FET of a
particular conductivity type on the substrate, including a first gate
electrode structure, a first source/drain region, and a first channel
region, wherein a first interface between the first source/drain region
and the first channel region is aligned to the first gate electrode
structure a first distance in the substrate from a center of the first
channel region; and a second FET of the particular conductivity type on
the substrate, including a second gate electrode structure, a second
source/drain region, and a second channel region, wherein the second
source/drain region wraps around a lower outer corner of the second gate
electrode structure in the substrate to form a second interface between
the second source/drain region and the second channel region a second
distance from a center of the second channel region that is less than the
first distance.

26. The circuit of claim 25 wherein the first and second FETs comprise
PMOS FETs, the first and second channel regions include a first material
comprising a first lattice constant and the first and second source/drain
regions include a second material comprising a second lattice constant
that is greater than the first lattice constant.

27. The circuit of claim 26 wherein the first material comprises Si and
the second material comprises SiGe.

28. The circuit of claim 25 wherein the first and second FETs comprise
NMOS FETs, the first and second channel regions include a first material
comprising a first lattice constant and the first and second source/drain
regions include a second material comprising a second lattice constant
that is less than the first lattice constant.

29. The circuit of claim 28 wherein the first material comprises Si and
the second material comprises SiC.

30. The circuit of claim 25 wherein the first and second source/drain
regions are both recessed below a surface of the substrate.

31. The circuit of claim 25 wherein the first and second channel regions
comprise respective fins that extend from the substrate to protrude from
a device isolation layer to provide upper side walls and a top surface of
the respective fins positioned between the first and second source/drain
regions, respectively.

32. The circuit of claim 25 wherein the first and second gate electrode
structures each include a first conductive gate layer in an outer portion
of the respective gate electrode structure and a second conductive gate
layer in an inner portion of the respective gate electrode structure, in
a recess defined by the first conductive gate layer.

33. The circuit of claim 32 wherein the first and second conductive gate
layers comprise first and second metal layers, respectively.

35. The circuit of claim 25 wherein the substrate comprises bulk silicon
or a silicon-on-insulator substrate.

36. The circuit of claim 25 wherein the first and second source/drain
regions comprise different lattice constants than the first and second
channel regions.

37. An integrated circuit comprising: a substrate; a first FET of a
particular conductivity type on the substrate, including a first gate
electrode structure, a first source/drain region, and a first channel
region, wherein the first source/drain region wraps around a lower outer
corner of the first gate electrode structure in the substrate to form a
first interface between the first source/drain region and the first
channel region a first distance from a center of the first channel
region; and a second FET of the particular conductivity type on the
substrate, including a second gate electrode structure, a second
source/drain region, and a second channel region, wherein the second
source/drain region wraps around a lower outer corner of the second gate
electrode structure in the substrate to form a second interface between
the second source/drain region and the second channel region a second
distance from a center of the second channel region that is less than the
first distance, so that the second source/drain region applies greater
stress to the second channel region than the first source/drain region
applies to the first channel region.

38. The circuit of claim 37 wherein the first and second source/drain
regions comprise different lattice constants than the first and second
channel regions, the circuit further comprising: a first stress film on
the first FET; and a second stress film on the second FET.

39. The circuit of claim 37 wherein the first and second source/drain
regions comprise different lattice constants than the first and second
channel regions.

40. The circuit of claim 37 wherein the first and second source/drain
regions are both recessed below a surface of the substrate.

41. An integrated circuit comprising: a substrate; a first FET of a
particular conductivity type on the substrate, including a first gate
electrode structure, a first spacer structure on a side wall of the first
gate electrode structure, a first source/drain region, and a first
channel region, wherein a first interface between the first source/drain
region and the first channel region is aligned to the first spacer
structure a first distance in the substrate from a center of the first
channel region; and a second FET of the particular conductivity type on
the substrate, including a second gate electrode structure, a second
spacer structure on a side wall of the second gate electrode structure
including more spacer layers than the first spacer structure, a second
source/drain region, and a second channel region, wherein a second
interface between the second source/drain region and the second channel
region is aligned to the second spacer structure a second distance in the
substrate from a center of the second channel region that is greater than
the first distance.

42. The circuit of claim 41 wherein the first and second FETs comprise
PMOS FETs, the first and second channel regions include a first material
comprising a first lattice constant and the first and second source/drain
regions include a second material comprising a second lattice constant
that is greater than the first lattice constant.

43. The circuit of claim 42 wherein the first material comprises Si and
the second material comprises SiGe.

44. The circuit of claim 41 wherein the first and second FETs comprise
NMOS FETs, the first and second channel regions include a first material
comprising a first lattice constant and the first and second source/drain
regions include a second material comprising a second lattice constant
that is less than the first lattice constant.

45. The circuit of claim 44 wherein the first material comprises Si and
the second material comprises SiC.

46. The circuit of claim 41 wherein the first and second source/drain
regions are both recessed below a surface of the substrate.

47. The circuit of claim 41 wherein the first and second channel regions
comprise respective fins that extend from the substrate to protrude from
a device isolation layer to provide upper side walls and a top surface of
the respective fins positioned between the first and second source/drain
regions, respectively.

48. An integrated circuit comprising: a first FET of a particular
conductivity type included in a logic region of a substrate; and a second
FET, of the particular conductivity type, in a Static Random Access
Memory region of the substrate, wherein a first source/drain region of
the first FET is spaced apart from a center of a first channel region of
the first FET differently than a second source/drain region of the second
FET is spaced apart from a center of a second channel region of the
second FET.

49. The circuit of claim 48 wherein a first interface between the first
source/drain region and the first channel region and a second interface
between the second source/drain region and the second channel region are,
separated from the centers of the first and second channel regions
differently.

Description:

[0001] This application claims priority from Korean Patent Application No.
10-2012-0043279 filed on Apr. 25, 2012 in the Korean Intellectual
Property Office, the disclosure of which is incorporated herein by
reference in its entirety.

BACKGROUND

[0002] 1. Field of the Inventive Concept

[0003] The present inventive concept relates to integrated circuit devices
and methods of fabricating the same.

[0004] 2. Description of the Related Art

[0005] Multi-gate transistors have been suggested as one of the scaling
technologies for increasing the density of a semiconductor device. In a
multi-gate transistor, a fin-shaped silicon body is formed on a
substrate, and a gate is formed on the surface of the silicon body.

[0006] Since the multi-gate transistor uses a 3D channel, scaling may be
more easily provided. In addition, the current control capability of the
multi-gate transistor can be improved even without an increase in a gate
length of the multi-gate transistor. Furthermore, a short channel effect
(SCE) in which the electric potential of a channel region is affected by
a drain voltage can be effectively suppressed or reduced.

SUMMARY

[0007] Embodiments according to the inventive concept can provide
integrated circuit devices including stress proximity effects and methods
of forming the same. Pursuant to these embodiments, an integrated circuit
can include first and second FETs of a particular conductivity type on a
substrate, wherein a first source/drain region of the first FET is closer
to a center of a first channel region of the first FET than a second
source/drain region of the second FET is to a center of a second channel
region of the second FET.

[0008] In some embodiments according to the inventive concept, a first
interface of the first source/drain region and the first channel region
is closer to the center of the first channel region than a second
interface of the second source/drain region and the second channel region
is to the center of the second channel region. In some embodiments
according to the inventive concept, the first and second source/drain
regions can have a particular lattice constant, and wherein the first
source/drain region applies greater stress to the first channel region
than the second source/drain region applies to the second channel region.

[0009] In some embodiments according to the inventive concept, the first
source/drain region extends past an outermost lower corner of a gate
structure of the first FET into the first channel region to define an
undercut region beneath the first FET, wherein the second source/drain
region is aligned to a gate structure of the second FET. In some
embodiments according to the inventive concept, the first and second
source/drain regions can be first and second raised source/drain regions,
respectively, wherein the first source/drain region extends past an
outermost lower corner of a gate structure of the first FET into the
first channel region to define a first undercut region beneath the first
FET. The second source/drain region can extend past an outermost lower
corner of a gate structure of the second FET into the second channel
region to define a second undercut region beneath the second FET.

[0010] In some embodiments according to the inventive concept, the first
and second source/drain regions can have different lattice constants than
the first and second channel regions. In some embodiments according to
the inventive concept, the first and second source/drain regions can be
first and second raised source/drain regions, respectively, wherein the
first raised source/drain region wraps around an outermost lower corner
of a gate structure of the first FET into the first channel region to
define an undercut region beneath the first FET and the second
source/drain region is formed aligned to a gate structure of the second
FET.

[0011] In some embodiments according to the inventive concept, the first
and second source/drain regions can be first and second raised
source/drain regions, respectively, wherein the first raised source/drain
region wraps around an outermost lower corner of a gate structure of the
first FET into the first channel region to define a first undercut region
beneath the first FET and the second raised source/drain region wraps
around an outermost lower corner of a gate structure of the second FET
into the second channel region to define a second undercut region beneath
the second FET.

[0012] In some embodiments according to the inventive concept, the device
can further include a first spacer including an outer side wall of a gate
structure of the first FET to provide a first thickness and a second
spacer including an outer side wall of a gate structure of the second FET
to provide a second thickness that is greater than the first thickness.
In some embodiments according to the inventive concept, the first
source/drain region is formed self-aligned to the first spacer and the
second source/drain region is formed self-aligned to the second spacer.
In some embodiments according to the inventive concept, a number of
layers included in the first spacer is less than a number of layers
included in the second spacer.

[0013] In some embodiments according to the inventive concept, the first
source/drain region is formed self-aligned to the first spacer and the
second source/drain region is formed self-aligned to the second spacer.
In some embodiments according to the inventive concept, the first and
second FETs can be PMOS FETs, the first and second channel regions
include a first material that can have a first lattice constant and the
first and second source/drain regions include a second material that can
have a second lattice constant that is greater than the first lattice
constant. In some embodiments according to the inventive concept, the
first material can be Si and the second material can be SiGe.

[0014] In some embodiments according to the inventive concept, the first
and second FETs can be NMOS FETs, the channel regions include a first
material that can have a first lattice constant and the source/drain
regions of the first and second FETs include a second material that can
have a second lattice constant that is less than the first lattice
constant. In some embodiments according to the inventive concept, the
first material can be Si and the second material can be SiC. In some
embodiments according to the inventive concept, the first and second
source/drain regions are both recessed below a surface of the substrate.
In some embodiments according to the inventive concept, the first and
second channel regions can be respective fins that extend from the
substrate to protrude from a device isolation layer to provide upper side
walls and a top surface of the respective fins positioned between the
first and second source/drain regions, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other aspects and features of the present inventive
concept will become more apparent by describing in detail exemplary
embodiments thereof with reference to the attached drawings, in which:

[0016] FIG. 1 is a perspective view of a semiconductor device according to
an embodiment of the present inventive concept.

[0017]FIG. 2 is a cross-sectional view taken along the line A-A' of FIG.
1.

[0018]FIG. 3 is a cross-sectional view taken along the lines B-B' and
C-C' of FIG. 1.

[0019]FIG. 4 is a cross-sectional view of a semiconductor device
according to an embodiment of the present inventive concept.

[0020]FIG. 5A is a cross-sectional view of a semiconductor device
according to an embodiment of the present inventive concept.

[0021]FIG. 5B is a cross-sectional view of a semiconductor device
according to an embodiment of the present inventive concept.

[0022]FIG. 6 is a cross-sectional view of a semiconductor device
according to an embodiment of the present inventive concept.

[0023]FIG. 7 is a cross-sectional view of a semiconductor device
according to an embodiment of the present inventive concept.

[0024] FIGS. 8 and 9 are respectively circuit and layout diagrams of a
semiconductor device according to an embodiment of the present inventive
concept.

[0025] FIG. 10A shows a plurality of fins and a plurality of gate
electrodes extracted from the layout diagram of FIG. 9.

[0026] FIG. 10B is a cross-sectional view taken along the lines D-D' and
E-E' of FIG. 9.

[0027] FIG. 11A is a diagram of a semiconductor device according to an
embodiment of the present inventive concept.

[0028] FIG. 11B is a diagram of a semiconductor device according to an
embodiment of the present inventive concept.

[0029] FIG. 11C is a diagram of a semiconductor device according to an
embodiment of the present inventive concept.

[0030]FIG. 12 is a diagram of a semiconductor device according to an
embodiment of the present inventive concept.

[0031]FIG. 13 is a diagram of a semiconductor device according to an
embodiment of the present inventive concept.

[0032] FIGS. 14 through 26 are diagrams illustrating intermediate
structures provided as portions of a method of fabricating the
semiconductor device according to an embodiment of the present inventive
concept.

[0033] FIGS. 27 through 30 are diagrams illustrating intermediate
structures provided as portions of a method of fabricating the
semiconductor device according to an embodiment of the present inventive
concept.

[0034] FIGS. 31 and 32 are diagrams illustrating intermediate structures
provided as portions of a method of fabricating the semiconductor device
according to an embodiment of the present inventive concept.

[0035] FIGS. 33 through 35 are diagrams illustrating a method of forming a
fin according to some embodiments of the present inventive concept.

[0036]FIG. 36 is a block diagram of an electronic system 1100 including a
semiconductor device according to some embodiments of the present
inventive concept.

[0037] FIGS. 37 and 38 are example semiconductor systems to which
semiconductor devices according to some embodiments of the present
inventive concept can be applied.

DETAILED DESCRIPTION OF EMBODIMENTS ACCORDING TO THE INVENTIVE CONCEPT

[0038] Advantages and features of the present invention and methods of
accomplishing the same may be understood more readily by reference to the
following detailed description of embodiments and the accompanying
drawings. The present invention may, however, be embodied in many
different forms and should not be construed as being limited to the
embodiments set forth herein. Rather, these embodiments are provided so
that this disclosure will be thorough and complete and will fully convey
the concept of the invention to those skilled in the art, and the present
invention will only be defined by the appended claims. Thus, in some
embodiments, well-known methods, procedures, components, and circuitry
have not been described in detail to avoid unnecessarily obscuring
aspects of the present invention.

[0039] It will be understood that, although the terms first, second, etc.
may be used herein to describe various elements, components, regions,
layers and/or sections, these elements, components, regions, layers
and/or sections should not be limited by these terms. These terms are
only used to distinguish one element, component, region, layer or section
from another element, component, region, layer or section. Thus, a first
element, component, region, layer or section discussed below could be
termed a second element, component, region, layer or section without
departing from the teachings of the present invention.

[0040] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of the
invention. As used herein, the singular forms "a," "an" and "the" are
intended to include the plural forms as well, unless the context clearly
indicates otherwise. It will be further understood that the terms
"comprises," "comprising," "includes" and/or "comprising," when used in
this specification, specify the presence of the stated features,
integers, steps, operations, elements, and/or components, but do not
preclude the presence or addition of one or more other features,
integers, steps, operations, elements, components, and/or groups thereof.

[0041] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this invention
belongs. It will be further understood that terms, such as those defined
in commonly used dictionaries, should be interpreted as having a meaning
that is consistent with their meaning in the context of the relevant art
and will not be interpreted in an idealized or overly formal sense unless
expressly so defined herein.

[0042] FIG. 1 is a perspective view of a semiconductor device according to
a first embodiment of the present inventive concept. FIG. 2 is a
cross-sectional view taken along the line A-A' of FIG. 1. FIG. 3 is a
cross-sectional view taken along the lines B-B' and C-C' of FIG. 1.

[0043] Referring to FIGS. 1 through 3, a first fin transistor 101 is
formed in a first region I, and a second fin transistor 201 is formed in
a second region II. The first region I and the second region II may be
separated or connected. The first region I may be, for example, a static
random access memory (SRAM) region, and the second region II may be a
logic region. Alternatively, the first region I may be a region in which
a pull-up transistor of an SRAM is formed, and the second region II may
be a region in which a pull-down transistor or a pass transistor of the
SRAM is formed.

[0044] The first fin transistor 101 has a first stress proximity, and the
second fin transistor 201 has a second stress proximity which is
different from the first stress proximity. Appropriate stress applied to
a channel (by, for example, different lattice constants) may improve the
mobility of carriers and increase the amount of current. As appreciated
by the present inventive step, how closely stress is applied to the
channel (such as relative to a center of the channel) may determine the
amount of strain on the channel. This is called a proximity effect.
Various methods can be used to make the first fin transistor 101 and the
second fin transistor 201 have different stress proximities. In the
semiconductor device shown in FIGS. 1-3, according to an embodiment of
the present inventive concept, a first distance L1 between a first gate
electrode 147 and a first source/drain 161 (e.g., first source/drain
region) and a second distance L2 between a second gate electrode 247 and
a second source/drain 261 (e.g., second source/drain region) are adjusted
to be different from each other, such that the first stress proximity and
the second stress proximity are different from each other.

[0045] It will be understood that the stress proximity effects discussed
herein can also be specified relative to a position in the channel region
associated with a respective source/drain region. For example, as shown
in FIG. 3, the stress proximity effects can also be specified by a
distance from the respective source/drain region to a center of the
channel region associated with the same fin transistor 201. In
particular, the first fin transistor 101 can experience a stress
proximity effect that is defined by the distance between the first
source/drain region 161 and a center of the channel region for the first
fin transistor 101. Similarly, the second fin transistor 101 can
experience a separate stress proximity effect that is defined by the
distance from the second source/drain region 261 to a center of the
channel region associated with the second fin transistor 201.
Accordingly, the stress proximity effects for the respective fin
transistors 101 and 201 can be specified by the distances L3 and L4
rather than the distances L1 and L2.

[0046] It will be further understood that the reference point for the
stress proximity effects can be defined relative to the interface between
the source/drain region and the channel region associated with the
respective transistor. For example, as described above, the distance L1
or L3 that is shown associated with the first fin transistor 101 can be
shown relative to the first source/drain region 161, which can be more
particularly defined by an interface location where the first
source/drain region 161 ends and the channel region associated with the
first fin transistor 101 begins. It will be understood that although this
reference location is defined as an interface, the actual location may
actually not be a particular location, as the source/drain and channel
regions may not define a clearly marked boundary but rather are subject
to the device physics associated with the diffusion of impurities. It
will be understood, however, that the interface location should be
interpreted as being a consistent reference point applied to the
different transistors.

[0047] The first fin transistor 101 may include a first fin F1, the first
gate electrode 147, a first recess 125, and the first source/drain 161.

[0048] The first fin F1 may extend along a second direction Y1. The first
fin F1 may be a part of a substrate 100 and may include an epitaxial
layer grown from the substrate 100. An element isolation film 110 may
cover lower side walls of the first fin F1 whereas upper side walls of
the first fin F1 are exposed.

[0049] The first gate electrode 147 may be formed on the first fin F1 to
intersect the first fin F1. The first gate electrode 147 may extend in a
first direction X1.

[0050] The first gate electrode 147 may include metal layers MG1 and MG2.
As shown in the drawings, the first gate electrode 147 may include a
stack of two or more metal layers MG1 and MG2. A first metal layer MG1
can control a work function, and a second metal layer MG2 fills a space
formed by the first metal layer MG1. The first metal layer MG1 may
include at least one of, e.g., TiN, TaN, TiC and TaC. In addition, the
second metal layer MG2 may include W or Al. Alternatively, the first gate
electrode 147 may be made of Si, SiGe, or the like rather than a metal.
The first gate electrode 147 may be formed using a replacement process,
however, other processes may be used.

[0051] A first gate insulating film 145 may be formed between the first
fin F1 and the first gate electrode 147. Referring to FIG. 2, the first
gate insulating film 145 may be formed on top and side surfaces of the
first fin F1. In addition, the first gate insulating film 145 may be
disposed between the first gate electrode 147 and the element isolation
film 110. The first gate insulating film 145 may include a high-k
material having a higher dielectric constant than a silicon oxide film.
For example, the first gate insulating film 145 may include HfO2, ZrO2,
or Ta2O5.

[0052] The first recess 125 may be formed in the first fin F1 on both
sides of the first gate electrode 147. The first recess 125 may have
sloping side walls. Thus, the first recess 125 may become wider as the
distance from the substrate 100 increases. As shown in FIG. 1, the first
recess 125 may be wider than the first fin F1.

[0053] The first source/drain 161 is formed in the first recess 125. The
first source/drain 161 may be an elevated source/drain. That is, a top
surface of the source/drain 161 may be higher than an upper surface of a
first interlayer insulating film 155. In addition, the first source/drain
161 and the first gate electrode 147 may be insulated from each other by
a spacer 151.

[0054] When the first fin transistor 101 is a p-channel metal oxide (PMOS)
transistor, the first source/drain 161 may include a compressive stress
material. The compressive stress material may be a material (e.g., SiGe)
having a lattice constant that is greater than that of Si. The
compressive stress material may apply compressive stress to the first fin
F1, thereby improving the mobility of carriers in a channel region.

[0055] On the other hand, when the first fin transistor 101 is an
n-channel metal oxide semiconductor (NMOS) transistor, the first
source/drain 161 may be the same material as the substrate 100 or a
tensile stress material. For example, when the substrate 100 is Si, the
first source/drain 161 may be Si or a material (e.g., SiC) having a
lattice constant that is less than that of Si.

[0056] The spacer 151 may include at least one of a nitride film and an
oxynitride film.

[0057] The substrate 100 may be made of one or more semiconductor
materials selected from the group consisting of Si, Ge, SiGe, GaP, GaAs,
SiC, SiGeC, InAs, and InP. The substrate 100 can also be a
silicon-on-insulator (SOI) substrate.

[0058] The second fin transistor 201 may include a second fin F2, the
second gate electrode 247, a second recess 225, and the second
source/drain 261. The second gate electrode 247 may be formed on the
second fin F2 to intersect the second fin F2, the second recess 225 may
be formed in the second fin F2 on both sides of the second gate electrode
247, and the second source/drain 261 may be formed in the second recess
225. The second fin transistor 201 is overall similar to the first fin
transistor 101, and thus differences from the first fin transistor 101
will mainly be described below.

[0059] In FIG. 1, the first fin F1 and the second fin F2 extend parallel
to each other in the second direction Y1 and Y2. However, this
illustration is merely for ease of description, and the present inventive
concept is not limited thereto. For example, the first fin F1 may extend
along the second direction Y1, and the second fin F2 may extend along the
first direction X2.

[0060] Likewise, while the first gate electrode 147 and the second gate
electrode 247 extend parallel to each other along the first direction X1
and X2 in FIG. 1, the present inventive concept is not limited thereto.
For example, the first gate electrode 147 may extend along the first
direction X1, and the second gate electrode 247 may extend along the
second direction Y2.

[0061] The first fin transistor 101 and the second fin transistor 201 may
be of the same conductivity type (e.g., a P type or an N type) sometimes
referred to herein as a particular conductive type. Alternatively, the
first fin transistor 101 may be of a first conductivity type (e.g., the P
type), and the second fin transistor 201 may be of a second conductivity
type (e.g., the N type).

[0063] Referring to FIG. 3, as described above, the first stress proximity
effect in the first fin transistor 101 is different from the second
stress proximity effect in the second fin transistor 201. Specifically,
the first distance L1 between the first gate electrode 147 and the first
source/drain 161 is different from the second distance L2 between the
second gate electrode 247 and the second source/drain 261, Here, `a
distance between a and b` denotes a shortest distance between a and b. As
shown in the drawing, the second distance L2 may be shorter than the
first distance L1.

[0064] As described above the distances L3 and L4 are alternatively used
to illustrate that the different stress proximity effects in the first
fin transistor 101 and the second fin transistor 201 can be specified by
the distance between the respective source/drain region and the center of
the channel of the respective transistor, rather than specifying between
the source/drain region and a particular portion of the gate electrode of
the respective first or second fin transistor 101 and 201.

[0065] As further shown in FIG. 3, the distances L2/L4 are less than L1/L3
respectively in that the interface of the second source/drain region 261
and the channel region associated with second fin transistor 201 extends
past an outer most lower corner of the respective second gate electrode
247 into the second channel region to define an undercut region beneath
the second fin transistor 201.

[0066] Since the first recess 125 and the second recess 225 are
respectively formed in the first source/drain 161 and the second
source/drain 261, the first distance L1/L3 and the second distance L2/L4
can be adjusted by adjusting the positions of the first recess 125 and
the second recess 225.

[0067] For example, if both of the first fin transistor 101 and the second
fin transistor 201 are P-type transistors, the substrate 100 may be Si,
and the first source/drain 161 and the second source/drain 261 may be
SiGe. In this case, since SiGe has a greater lattice constant than Si,
the first source/drain 161 may apply compressive stress to the channel
region of the first fin transistor 101, and the second source/drain 261
may apply compressive stress to the channel region of the second fin
transistor 201. However, since the first distance L1/L3 is longer than
the second distance L2/L4, the compressive stress applied to the channel
region of the first fin transistor 101 by the first source/drain 161 may
be less than the compressive stress applied to the channel region of the
second fin transistor 201 by the second source/drain 261. Accordingly,
the first fin transistor 101 may have less current than the second fin
transistor 201.

[0068] When a fin having a very small width (e.g., a width of 20 nm or
less) is formed, a conventional photo process may not be used. For
example, a sidewall image transfer (SIT) process in which a fin with a
predetermined width is formed repeatedly may be used. In this case, it
may be more difficult to adjust an effective channel width. That is, in
the case of a conventional planar transistor, the amount of current can
be more readily adjusted by changing the channel width using a photo
process. However, in the case of a fin transistor using fins formed by
the SIT process, it may be more difficult to adjust the amount of current
since the channel width is fixed. That is, the amount of current can be
adjusted only by changing the number of fins. For example, when one fin
is used, the amount of current of a fin transistor is k. When two fins
are used, the amount of current of the fin transistor is 2 k. That is, it
is difficult to finely adjust the amount of current.

[0069] In the semiconductor device according to the first embodiment of
the present inventive concept, however, the current of the first and
second fin transistors 101 and 201 can be controlled by adjusting the
first and second distances L1/L3 and L2/L4 between the first and second
gate electrodes 147 and 247 (or centers of respective channel regions)
and the first and second sources/drains 161 and 261.

[0070]FIG. 4 is a cross-sectional view of a semiconductor device
according to a second embodiment of the present inventive concept. For
simplicity, the following description will focus on differences from the
semiconductor device according to the first embodiment of the present
inventive concept.

[0071] Referring to FIG. 4, a first distance L1/L3 between a first gate
electrode 147 (or the center of the channel region) and a first
source/drain 161 in a first fin transistor 102 is different from a second
distance L2/L4 between a second gate electrode 247 (or the center of the
channel region) and a second source/drain 261 in a second fin transistor
202. An amount of undercut of a first recess 125 is different from an
amount of undercut of a second recess 225. As shown in the drawing, the
amount of undercut of the second recess 225 is greater than that of the
first recess 125. Therefore, even though both source/drain regions
exhibit undercut, the undercut of the second source/drain region 261 is
greater.

[0072] Further, a first stress film 169 may be formed on the first fin
transistor 102, and a second stress film 269 may be formed on the second
fin transistor 202.

[0073] Each of the first stress film 169 and the second stress film 269
may be, for example, a SiN film. Whether the SiN film applies tensile
stress or compressive stress is determined by a ratio of N--H bonding to
Si--H bonding in the SiN film. For example, the SiN film may apply the
tensile stress when the ratio of N--H bonding/Si--H bonding is
approximately 1 to 5 and apply the compressive stress when the ratio of
N--H bonding/Si--H bonding is approximately 5 to 20.

[0074] For example, if both of the first fin transistor 102 and the second
fin transistor 202 are PMOS transistors, the current of the second fin
transistor 202 may be greater than the current of the first fin
transistor 102. The first stress film 169 and the second stress film 269
may have the effect of increasing the current of both the first fin
transistor 102 and the second fin transistor 202.

[0075]FIG. 5A is a cross-sectional view of a semiconductor device
according to an embodiment of the present inventive concept. For
simplicity, the following description will focus on differences from the
semiconductor device according to the first embodiment of the present
inventive concept.

[0076] Referring to FIG. 5A, a first spacer 151 is disposed on sidewalls
of a first gate electrode 147 of a first fin transistor 103. In addition,
a second spacer 251 is disposed on sidewalls of a second gate electrode
247 of a second fin transistor 203. As shown in the drawing, a first
thickness of the first spacer 151 is different from a second thickness of
the second spacer 251.

[0077] To make the first spacer 151 and the second spacer 251 have
different thicknesses, the first spacer 151 may include n (where n is a
natural number) layers, and the second spacer 251 may include (n+m)
(where m is a natural number) layers. In the drawing, the first spacer
151 includes two insulating layers 151a and 151b, and the second spacer
251 includes three insulating layers 251a, 251b and 251c.

[0078] A first recess 125 may be formed using the first spacer 151 as a
mask, and a second recess 225 may be formed using the second spacer 251
as a mask. That is, the first recess 125 may be aligned with the first
spacer 151, and the second recess 225 may be aligned with the second
spacer 251. However, the present inventive concept is not limited
thereto. The first recess 125 may include an undercut and extend to under
the first spacer 151, and the second recess 225 may include an undercut
and extend to under the second spacer 251 as described herein in
reference to FIGS. 3 and 4.

[0079] Since the first spacer 151 and the second spacer 251 have different
thicknesses, the first recess 125 and the second recess 225 may be
located at different positions. As shown in the drawing, since the second
spacer 251 is thicker than the first spacer 151, a second distance L2/L4
may be greater than a first distance L1/L3. In this case, if both of the
first fin transistor 103 and the second fin transistor 203 are PMOS
transistors, the first fin transistor 103 may have a greater amount of
current than the second fin transistor 203.

[0080]FIG. 5B is a cross-sectional view of a semiconductor device
according to an embodiment of the present inventive concept. For
simplicity, the following description will focus on differences from the
semiconductor device according to the first embodiment of the present
inventive concept.

[0081] Referring to FIG. 5B, a distance L1/L3 between a first gate
electrode 147 (or center of the channel region) and a first source/drain
161 in a first fin transistor 103a may be equal to a distance L2/L4
between a second gate electrode 247 (or center of the channel region) and
a second source/drain 261 in a second fin transistor 203a.

[0082] Stress applied to a channel of the first fin transistor 103a by a
first spacer 151 may be different from stress applied to a channel of the
second fin transistor 203a by a second spacer 251. For example, different
materials may be used to form the first spacer 151 and the second spacer
251. Specifically, insulating layers 151a and 151b of the first spacer
151 and an insulating layer 251b of the second spacer 251 may not be
materials that apply stress to a channel. However, an insulating layer
251d of the second spacer 251 may be a material that applies stress to
the channel of the second fin transistor 203a. As a result, an amount of
current of the first fin transistor 103a may be different from an amount
of current of the second fin transistor 203a.

[0083]FIG. 6 is a cross-sectional view of a semiconductor device
according to an embodiment of the present inventive concept. For
simplicity, the following description will focus on differences from the
semiconductor device according to the first embodiment of the present
inventive concept.

[0084] Referring to FIG. 6, a first distance L1/L3 associated with a first
fin transistor 104 may be substantially equal to a second distance L2/L4
associated with a second fin transistor 204.

[0085] Here, the first fin transistor 104 and the second fin transistor
204 are of the same conductivity type, and an impurity concentration of a
source/drain 161 formed in a first recess 125 is different from an
impurity concentration of a second source/drain 261 formed in a second
recess 225. For example, when the impurity concentration of the second
source/drain 261 is greater than that of the first source/drain 161, a
resistance of the second source/drain 261 may be less than that of the
first source/drain 161. Accordingly, the second fin transistor 204 may
have a greater amount of current than the first fin transistor 104. That
is, the amount of current can be adjusted by controlling the impurity
concentration of each of the first source/drain 161 and the second
source/drain 261.

[0086]FIG. 7 is a cross-sectional view of a semiconductor device
according to an embodiment of the present inventive concept. For
simplicity, the following description will focus on differences from the
semiconductor device according to the first embodiment of the present
inventive concept.

[0087] Referring to FIG. 7, in the semiconductor device according to an
embodiment of the present inventive concept, an amount of current of a
fin transistor can be adjusted using a combination of features (such as
adjusting a distance between a gate electrode or a center of a channel
region and a source/drain (or a source/drain channel interface),
adjusting the impurity concentration, and using a stress film).

[0088] That is, a first spacer 151 is disposed on sidewalls of a first
gate electrode 147 of a first fin transistor 105, and a second spacer 251
is disposed on sidewalls of a second gate electrode 247 of a second fin
transistor 205. A first thickness of the first spacer 151 is different
from a second thickness of the second spacer 251.

[0089] In addition, an impurity concentration of the first source/drain
161 formed in a first recess 125 is different from an impurity
concentration of the second source/drain 261 formed in a second recess
225.

[0090] Further, a first stress film 169 may be formed on the first fin
transistor 105, and a second stress film 269 may be formed on the second
fin transistor 205.

[0091] In FIG. 7, a case where the impurity concentration of the first
source/drain 161 is different from the impurity concentration of the
second source/drain 261 is illustrated as an example. However, the
present inventive concept is not limited to this case. For example, the
concentration of a material (e.g., SiGe) that fills the first
source/drain 161 may be different from the concentration of a material
that fills the second source/drain 261. In this case, stress applied to a
channel of the first fin transistor 105 may also be different from stress
applied to a channel of the second fin transistor 205.

[0092] FIGS. 8 and 9 are a circuit and a layout diagram, respectively, of
a semiconductor device according to an embodiment of the present
inventive concept. FIG. 10A shows a plurality of fins and a plurality of
gate electrodes extracted from the layout diagram of FIG. 9. FIG. 10B is
a cross-sectional view taken along the lines D-D' and E-E' of FIG. 9.
While the above-described semiconductor devices according to the
embodiments of the present inventive concept are applicable to all
structures or devices that use a fin transistor, an SRAM is illustrated
as an example in FIGS. 8 through 10B.

[0093] Referring to FIG. 8, the semiconductor device according to the
sixth embodiment of the present inventive concept may include a pair of
inverters INV1 and INV2 connected in parallel between a power supply node
Vcc and a ground node Vss and first and second pass transistors PS1 and
PS2 connected respectively to output nodes of the inverters INV1 and
INV2. The first pass transistor PSI and the second pass transistor PS2
may be connected to a bit line BL and a complementary bit line BL/,
respectively. A gate of the first pass transistor PS1 and a gate of the
second pass transistor PS2 may be connected to a word line WL.

[0094] A first inverter INV1 includes a first pull-up transistor PU1 and a
first pull-down transistor PD1 connected in series to each other, and a
second inverter INV2 includes a second pull-up transistor PU2 and a
second pull-down transistor PD2 connected in series to each other. The
first pull-up transistor PU1 and the second pull-up transistor PU2 may be
PMOS transistors, and the first pull-down transistor PD1 and the second
pull-down transistor PD2 may be NMOS transistors.

[0095] In addition, an input node of the first inverter INV1 is connected
to an output node of the second inverter INV2, and an input node of the
second inverter INV2 is connected to an output node of the first inverter
INV1, so that the first inverter INV1 and the second inverter INV2 form
one latch circuit.

[0096] Referring to FIGS. 8 through 10B, first through fourth fins 310
through 340 are separated from each other and extend in a direction
(e.g., a vertical direction in FIG. 9). The second fin 320 and the third
fin 330 may be shorter than the first fin 310 and the fourth fin 340.

[0097] In addition, first through fourth gate electrodes 351 through 354
extend in the other direction (e.g., a horizontal direction in FIG. 9)
and intersect the first through fourth fins 310 through 340.
Specifically, the first gate electrode 351 may completely intersect the
first fin 310 and the second fin 320 and overlap an end of the third fin
330. The third gate electrode 353 may completely intersect the fourth fin
340 and the third fin 330 and overlap an end of the second fin 320. The
second gate electrode 352 and the fourth gate electrode 354 intersect the
first fin 310 and the fourth fin 340, respectively.

[0098] As shown in the drawings, the first pull-up transistor PU1 is
defined in a region in which the first gate electrode 351 intersects the
second fin 320, the first pull-down transistor PD1 is defined in a region
in which the first gate electrode 351 intersects the first fin 310, and
the first pass transistor PSI is defined in a region in which the second
gate electrode 352 intersects the first fin 310. The second pull-up
transistor PU2 is defined in a region in which the third gate electrode
353 intersects the third fin 330, the second pull-down transistor PD2 is
defined in a region in which the third gate electrode 353 intersects the
fourth fin 340, and the second pass transistor PS2 is defined in a region
in which the fourth gate electrode 354 intersects the fourth fin 340.

[0099] A recess may be formed on both sides of each of the regions in
which the first through fourth gate electrodes 351 through 354 intersect
the first through fourth fins 310 through 340, and a source/drain may be
formed in the recess. A plurality of contacts 350 may be formed,

[0100] Furthermore, a shared contact 361 connects all of the second fin
320, a third gate electrode 353, and a wiring 371. A shared contact 362
connects all of the third fin 330, the first gate electrode 351, and a
wiring 372.

[0101] The first pull-up transistor PU1, the first pull-down transistor
PD1, the first pass transistor PS1, the second pull-up transistor PU2,
the second pull-down transistor PD2, and the second pass transistor PS2
may all be implemented as fin transistors and may be configured as
described above with reference to, for example, FIGS. 1 through 7.

[0102] For example, the above transistors may be configured as shown in
FIG. 10B. The first pull-up transistor PU1 may include the second fin
320, the first gate electrode 351 which intersects the second fin 320, a
first recess 321a which is formed in the second fin 320 on both sides of
the first gate electrode 351, and a first source/drain 321 which is
formed in the first recess 321a. The first pull-down transistor PD1 may
include the first fin 310, the first gate electrode 351 which intersects
the first fin 310, a second recess 311a which is formed in the first fin
310 on both sides of the first gate electrode 351, and a second
source/drain 311 which is formed in the second recess 311a.

[0103] In this case, a distance L3/L5 between the first gate electrode 351
(or center of the channel region) and the first source/drain 321 of the
first pull-up transistor PU1 may be different from a distance L4/L6
between the first gate electrode 351 (or center of the channel region)
and the second source/drain 311 of the first pull-down transistor PD1. To
reduce the consumption of current, for example, an amount of current of
the first pull-up transistor PU1 may be reduced. Therefore, the distance
L3/L5 may be greater than the distance L4/L6.

[0104] The first pass transistor PS1 may include the first fin 310, the
second gate electrode 352 which intersects the first fin 310, a third
recess which is formed in the first fin 310 on both sides of the second
gate electrode 352, and a third source/drain which is formed in the third
recess. As shown in the drawings, the second source/drain and the third
source/drain share one node. The distance L3/L5 between the first gate
electrode 351 (or center of the channel region) and the first
source/drain 321 of the first pull-up transistor PU1 may be different
from a distance between the second gate electrode 352 (or center of the
channel region) and the third source/drain of the first pass transistor
PS1. In addition, the distance L3/L5 between the first gate electrode 351
(or center of the channel region) and the first source/drain 321 of the
first pull-up transistor PU1 may be longer than the distance between the
second gate electrode 352 (or center of the channel region) and the third
source/drain of the first pass transistor PS1.

[0105] Referring to FIG. 10A, a process of forming recesses in the first
pull-up transistor PU1 and the second pull-up transistor PU2 of a first
region I may be performed separately from a process of forming recesses
in the first pull-down transistor PD1, the second pull-down transistor
PD2, the first pass transistor PS1, and the second pass transistor PS2 of
a second region II.

[0106] In so doing, the amount of current of the first pull-up transistor
PU1 and the second pull-up transistor PU2 can be reduced.

[0107] FIG. 11A is a diagram of a semiconductor device according to an
embodiment of the present inventive concept.

[0108] Referring to FIG. 11A, in the semiconductor device according to the
embodiment of the present inventive concept, a fin transistor 411 may be
disposed in a logic region 410, and a fin transistor 421 may be disposed
in an SRAM region 420.

[0109] A distance between a gate electrode (or center of a channel region)
and a source/drain of the fin transistor 411 and a distance between a
gate electrode (or center of the channel region) and a source/drain of
the fin transistor 421 may be adjusted to be different. Moreover, stress
applied to a channel of the fin transistor 411 and stress applied to a
channel of the fin transistor 421 may be adjusted to be different.

[0110] In FIG. 11A, the logic region 410 and the SRAM region 420 are
illustrated as an example. However, the present inventive concept is not
limited to this example. The present inventive concept is also applicable
to a case where the logic region 410 and a region in which another memory
(e.g., DRAM, MRAM, RRAM, PRAM, or the like) is formed are provided.

[0111] FIG. 11B is a diagram of a semiconductor device according to an
embodiment of the present inventive concept.

[0112] Referring to FIG. 11B, in the semiconductor device according to the
embodiment of the present inventive concept, different fin transistors
412 and 422 may be disposed in a logic region 410.

[0113] That is, a distance between a gate electrode (or center of the
channel region) and a source/drain of the fin transistor 412 and a
distance between a gate electrode (or center of the channel region) and a
source/drain of the fin transistor 422 may be adjusted to be different.
Moreover, stress applied to a channel of the fin transistor 412 and
stress applied to a channel of the fin transistor 422 may be adjusted to
be different.

[0114] FIG. 11C is a diagram of a semiconductor device according to an
embodiment of the present inventive concept.

[0115] Referring to FIG. 11C, in the semiconductor device according to the
embodiment of the present inventive concept, a plurality of blocks, e.g.,
BLK1 and BLK2 are defined in a substrate. Here, different fin transistors
may be disposed in each of the blocks BLK1 and BLK2. As shown in the
drawing, one or more fins F5 or F6 may be disposed in each of the blocks
BLK1 and BLK2. A distance between a gate electrode (or center of the
channel region) and a source/drain of a fin transistor disposed in the
block BLK1 and a distance between a gate electrode (or center of the
channel region) and a source/drain of a fin transistor disposed in the
block BLK2 may be adjusted to be different. Moreover, stress applied to a
channel of the fin transistor disposed in the block BLK1 and stress
applied to a channel of the fin transistor disposed in the block BLK2 may
be adjusted to be different.

[0116]FIG. 12 is a diagram of a semiconductor device according to an
embodiment of the present inventive concept. For simplicity, the
following description will focus on differences from the semiconductor
device according to the first embodiment of the present inventive
concept.

[0117] Referring to FIG. 12, in the semiconductor device according to the
embodiment of the present inventive concept, an amount of current of a
fin transistor 106 or 106a is adjusted by controlling the number of fins
F11 and F12 or F21 and F22 used.

[0118] The fin transistor 106 includes a plurality of first fins F11 and
F12 which are separated from each other and parallel to each other. A
first gate electrode 147 may intersect the first fins F11 and F12. The
fin transistor 106a includes a plurality of second fins F21 and F22 which
are separated from each other and parallel to each other. A second gate
electrode 247 may intersect the second fins F21 and F22.

[0119] A distance between the first gate electrode 147 (or center of the
channel region) and a source/drain of the fin transistor 106 may be
different from a distance between the second gate electrode 247 (or
center of the channel region) and a source/drain of the fin transistor
106a. Additionally or alternatively, an impurity concentration of the
source/drain of the fin transistor 106 may be different from an impurity
concentration of the source/drain of the fin transistor 106a.

[0120] When the number of fins F11 and F12 used by the fin transistor 106
increases, the amount of current may increase. That is, if the amount of
current of the fin transistor 106 is j when one fin is used, it becomes
2j when two fins F11 and F12 are used. In addition, as described above,
the amount of current of the fin transistor 106a may be adjusted to be a
little different from the amount of current of the fin transistor 106.
For example, the amount of current of the fm transistor 106a may be
approximately 2j+α or 2j-α.

[0121] Therefore, according to the embodiment of the present inventive
concept, fin transistors 106 and 106a having various amounts of current
can be implemented.

[0122] FIG, 13 is a diagram of a semiconductor device according to an
embodiment of the present inventive concept. For simplicity, the
following description will focus on differences from the semiconductor
device according to the eighth embodiment of the present inventive
concept.

[0123] Referring to FIG. 13, in the semiconductor device according to the
embodiment of the present inventive concept, amounts of current of fin
transistors 108, 107, 106 and 101 can be adjusted by controlling the
number of fins F1a, F1b, F2a, F2b, F3a, F3b, F4a, and F4b used.

[0124] Fin transistors 108 and 108a each use four fins F1a or F2a. If an
amount of current of a fin transistor is j when one fin is used, the
amount of current of the fin transistor 108 using four fins F1a is 4j. In
addition, the amount of current of the fin transistor 108a may be
approximately 4j+α or 4j-α.

[0125] Fin transistors 107 and 107a each use three fins F1b or F2b. The
amount of current of the fin transistor 107 using three fins F1b is 3j.
In addition, the amount of current of the fin transistor 107a may be
approximately 3j+α or 3j-α.

[0126] Fin transistors 106 and 106a each use two fins F1c or F2c. The
amount of current of the fin transistor 106 using two fins F1c is 2j. In
addition, the amount of current of the fin transistor 106a may be
approximately 2j+α or 2j-α.

[0127] Fin transistors 101 and 101a each use one fin F1d or F2d. The
amount of current of the fin transistor 101 using one fin F1d is j. In
addition, the amount of current of the fin transistor 101a may be
approximately j+α or j-α.

[0128] Therefore, according to the embodiment of the present inventive
concept, fin transistors 108, 108a, 107, 107a, 106, 106a, 101 and 101a
having various amounts of current can be implemented.

[0129] FIGS. 14 through 26 are diagrams illustrating intermediate
structures provided in methods of fabricating semiconductor devices
according to embodiments of the present inventive concept. In FIGS. 14
through 20, only a first fin transistor 101 (see FIG. 1) is illustrated,
as fabricating the first fin transistor 101 is substantially the same as
fabricating a second fin transistor 201 (see FIG. 1). In FIGS. 21 through
26, the first fin transistor 101 and the second fin transistor 201 are
illustrated. FIGS. 22 and 25 are cross-sectional views taken along the
line A-A' of FIGS. 21 and 24, respectively. FIGS. 23 and 26 are
cross-sectional views taken along the lines B-B' and C-C' of FIG. 24,
respectively.

[0130] Referring to FIG. 14, a first fin F1 is formed in a first region I.
Specifically, a mask pattern 2103 is formed on a substrate 100, and then
an etching process is performed to form the first fin F1. The first fin
F1 may extend along a second direction Y1. A trench 121 is formed around
the first fin F1. The mask pattern 2103 may be made of a material that
includes at least one of a silicon oxide film, a silicon nitride film,
and a silicon oxynitride film.

[0131] Referring to FIG. 15, an element isolation film 110 is formed to
fill the trench 121. The element isolation film 110 may be made of a
material that includes at least one of a silicon oxide film, a silicon
nitride film, and a silicon oxynitride film.

[0132] Referring to FIG. 16, an upper part of the element isolation film
110 is recessed to expose an upper part of the first fin F1 including
upper sidewalls thereof. The recess process may include a selective
etching process. The mask pattern 2103 may be removed before or after the
formation of the element isolation film 110.

[0133] A part of the first fin F1 which protrudes upward from the element
isolation film 110 may be formed by an epitaxial process. Specifically,
after the element isolation film 110 is formed, an epitaxial process may
be performed using a top surface of the first fin F1, which is exposed by
the element isolation film 110, as a seed. As a result, the protruding
part of the first fin F1 (including the upper side walls) may be formed
without a recess process.

[0134] In addition, a doping process for controlling a threshold voltage
may be performed on the first fin F1. When the first fin transistor 101
is an NMOS transistor, impurities may be B. When the first fin transistor
101 is a PMOS transistor, the impurities may be P or As.

[0135] Referring to FIG. 17, an etching process is performed using a mask
pattern 2104, thereby forming a dummy gate insulating film 141 and a
first dummy gate electrode 143 which intersect the first fin F1 and
extend in a first direction X1.

[0136] For example, the dummy gate insulating film 141 may be a silicon
oxide film, and the first dummy gate electrode 143 may be polysilicon.

[0137] Referring to FIG. 18, a first spacer 151 is formed on side walls of
the first dummy gate electrode 143 and upper side walls of the first fin
F1.

[0138] For example, an insulating layer may be formed on the resultant
structure (of FIG. 17) having the first dummy gate electrode 143, and
then an etch-back process may be performed, thereby forming the first
spacer 151. The first spacer 151 may expose a top surface of the mask
pattern 2104 and the top surface of the first fin F1. The first spacer
151 may be a silicon nitride film or a silicon oxynitride film.

[0139] Referring to FIG. 19, an interlayer insulating film 155 is formed
on the resultant structure (of FIG. 18) having the first spacer 151. The
interlayer insulating film 155 may be a silicon oxide film.

[0140] Next, the interlayer insulating film 155 is planarized until a top
surface of the first dummy gate electrode 143 is exposed. As a result,
the mask pattern 2104 is removed, thereby exposing the top surface of the
first dummy gate electrode 143.

[0141] Referring to FIG. 20, the dummy gate insulating film 141 and the
first dummy gate electrode 143 are removed. The removal of the dummy gate
insulating film 141 and the first dummy gate electrode 143 results in the
formation of a trench 123 which exposes the element isolation film 110.

[0142] Referring to FIGS. 21 through 23, a first gate insulating film 145
and a first gate electrode 147 are formed in the trench 123.

[0143] The first gate insulating film 145 may include a high-k material
having a higher dielectric constant than a silicon oxide film. The first
gate insulating film 145 may include, for example, HfO2, ZrO2,
or Ta2O5. The first gate insulating film 145 may be
substantially conformally formed along sidewalls and a bottom surface of
the trench 123.

[0144] The first gate electrode 147 may include metal layers MG1 and MG2.
As shown in the drawings, the first gate electrode 147 may include a
stack of two or more metal layers MG1 and MG2. A first metal layer MG1
controls a work function, and a second metal layer MG2 fills a space
formed by the first metal layer MG1. The first metal layer MG1 may
include at least one of e.g., TiN, TaN, TiC and TaC. In addition, the
second metal layer MG2 may include W or Al. Alternatively, the first gate
electrode 147 may be made not of metal but of Si, SiGe, or the like.

[0145] In the same way as described above, a second gate insulating film
245 and a second gate electrode 247 are formed in a second region II. The
second gate electrode 247 may include metal layers MG3 and MG4.

[0146] Referring to FIGS. 24 through 26, a first recess 125 is formed in
the first fin F1 on both sides of the first gate electrode 147 in the
first region I, and a second recess 225 is formed in a second fin F2 on
both sides of the second gate electrode 247 in the second region II.

[0147] Here, the first recess 125 and the second recess 225 may be formed
such that a first distance L1/L3 between the first gate electrode 147 (or
center of the channel region) and the first recess 125 is different from
a second distance L2/L4 between the second gate electrode 247 (or center
of the channel region) and the second recess 225. The forming of the
first recess 125 may be performed separately from the forming of the
second recess 225.

[0148] For example, a first wet-etching process may be performed for a
first period of time using a first mask which exposes the first region I
but does not expose the second region II. Then, a second wet-etching
process may be performed for a second period of time which is different
from the first period of time using a second mask which exposes the
second region II but does not expose the first region I.

[0149] Additionally or alternatively, an etchant used to form the first
recess 125 may be different from an etchant used to form the second
recess 225.

[0150] For example, the first recess 125 may not include an undercut, and
the second recess 225 may include an undercut. Alternatively, an amount
of undercut of the first recess 125 and an amount of undercut of the
second recess 225 may be adjusted to be different. Accordingly, the first
distance L1/L3 and the second distance L2/L4 may become different.

[0151] Referring to FIGS. 1 through 3, a first source/drain 161 is formed
in the first recess 125, and a second source/drain 261 is formed in the
second recess 225. The first source/drain 161 may be, for example, an
elevated source/drain. That is, a top surface of the first source/drain
161 may be higher than a bottom surface of the first interlayer
insulating film 155.

[0152] The forming of the first source/drain 161 and the forming of the
second source/drain 261 may be achieved by an epitaxial process. In
addition, the material that forms the first source/drain 161 and the
second source/drain 261 may vary according to whether the first fin
transistor 101 and the second fin transistor 201 are PMOS transistors or
NMOS transistors.

[0153] Impurities may be doped in situ during the epitaxial process.

[0154] FIGS. 27 through 30 are diagrams illustrating intermediate
structures provided in methods of fabricating semiconductor devices
according to the embodiments of the present inventive concept. For
simplicity, the following description will focus on differences from the
fabrication method described above with reference to FIGS, 14 through 26.
The methods of fabricating the semiconductor device according to the
embodiment of the present inventive concept is substantially the same as
the methods of fabricating the semiconductor devices according to the
first embodiment of the present inventive concept, except forming a
spacer (that is, a process of FIG. 18).

[0155] Referring to FIG. 27, n (where n is a natural number) insulating
layers 451a and 451b are formed on a first region I and a second region
II. In the drawing, a case where n is two is illustrated. However, the
present inventive concept is not limited to this case.

[0156] Referring to FIG. 28, the two insulating layers 451a and 451b are
etched back using a first mask 460 which exposes the first region I but
does not expose the second region II. As a result, a first spacer 151 is
formed on sidewalls of a first dummy gate electrode 143. Then, the first
mask 460 is removed.

[0157] Referring to FIG. 29, a second mask 470 which exposes the second
region II but does not expose the first region I is formed. Then, m
(where, m is a natural number) insulating layers 451c are formed on the
second region II. In the drawing, a case where m is one is illustrated as
an example. However, the present inventive concept is not limited to this
case.

[0158] Referring to FIG. 30, the insulating layers 451a, 451b and 451c are
etched back using the second mask 470. As a result, a second spacer 251
is formed on sidewalls of a second dummy gate electrode 241

[0159] In summary, to make the first spacer 151 of the first region I and
the second spacer 251 of the second region II have different thicknesses,
the first spacer 151 is formed by etching back n insulating layers 451a
and 451b formed on the first region I. Then, the second spacer 251 is
formed by etching back (n+m) insulating layers 451a, 451b and 451c formed
on the second region II.

[0160] FIGS. 31 and 32 are diagrams illustrating intermediate structures
provided in methods of fabricating semiconductor devices according to the
embodiments of the present inventive concept. For simplicity, the
following description will focus on differences from the fabrication
methods described above with reference to FIGS. 14 through 26. The
methods of fabricating the semiconductor devices according to the
embodiment of the present inventive concept is substantially the same as
the methods of fabricating the semiconductor devices according to the
embodiment of the present inventive concept as shown above, except for a
process of forming a recess (that is, see FIGS. 24 through 26) and a
process of forming a source/drain (that is, an epitaxial process).

[0161] Referring to FIGS. 31 and 32, a first distance L1/L3 between a
first gate electrode 147 (or center of the channel region) and a first
recess 125 is substantially equal to a second distance L2/L4 between a
second gate electrode 247 (or center of the channel region) and a second
recess 225, unlike in FIGS. 24 through 26.

[0162] Referring to FIG. 32, a third mask 480 which exposes a first region
I but does not expose a second region II is formed. An epitaxial process
is performed while the first recess 125 is in-situ doped with impurities
to a first impurity concentration. As a result, a first source/drain 161
is formed. Then, the third mask 480 is removed.

[0163] Referring to FIG. 6, a fourth mask which exposes the second region
II but does not expose the first region I is formed. An epitaxial process
is performed while the second recess 225 is in-situ doped with impurities
to a second impurity concentration. As a result, a second source/drain
261 is formed.

[0164] Hereinafter, methods of forming a fin usable in methods of
fabricating semiconductor device according to some embodiments of the
present inventive concept will be described with reference to FIGS. 33
through 35. The methods in FIGS. 33 through 35 may be methods of forming
a plurality of fins illustrated in FIG. 12. The methods may include, for
example, a SIT process. In FIGS. 33 through 35, methods of forming two
fins are illustrated as an example. However, the present inventive
concept is not limited to this example.

[0165] Referring to FIG. 33, a sacrificial pattern 501 is formed on a
substrate 100. Then, a mask layer 505 is formed on the substrate 100
having the sacrificial pattern 501. The mask layer 505 may be conformally
formed along a top surface of the substrate 100 having the sacrificial
pattern 501. The sacrificial pattern 501 and the mask layer 505 may be
made of materials that have an etch selectivity with respect to each
other. For example, the mask layer 505 may include at least one of
silicon oxide, silicon nitride, silicon oxynitride, photoresist, spin on
glass (SOG) and spin on hard mask (SOH), and the sacrificial pattern 501
may be made of one of the above materials which is different from the
material of the mask layer 505.

[0166] The sacrificial pattern 501 and the mask layer 505 may be formed by
at least one of a physical vapor deposition (PVD) process, a chemical
vapor deposition (CVD) process, an atomic layer deposition (ALD) process,
and a spin coating process.

[0167] Referring to FIG. 34, spacer-shaped mask patterns 506 are
respectively formed on side walls of the sacrificial pattern 501 using an
etch-back process. Then, the sacrificial pattern 501 is removed. The mask
patterns 506 may have substantially the same width. A trench 511 may be
formed between the mask patterns 506.

[0168] Referring to FIG. 35, the substrate 100 is etched using the mask
patterns 506 as an etch mask. As a result, fins F11 and F22 having a
predetermined width may be formed. A trench 512 may be formed between the
adjacent fins F11 and F12 by an etching process. In the etching process,
upper parts of the mask patterns 506 may also be etched. Thus, the upper
parts of the mask patterns 506 may become round.

[0169] The mask patterns 506 may be removed, thereby completing the fins
F11 and F12 which are separated from each other and have the
predetermined width.

[0170]FIG. 36 is a block diagram of an electronic system 1100 including a
semiconductor device according to some embodiments of the present
inventive concept.

[0171] Referring to FIG. 36, the electronic system 1100 according to an
embodiment of the present inventive concept may include a controller
1110, an input/output (I/O) device 1120, a memory device 1130, an
interface 1140, and a bus 1150. The controller 1110, the I/O device 1120,
the memory device 1130, and/or the interface 1140 may be coupled to each
other through the bus 1150. The bus 1150 corresponds to a path through
which data is transferred.

[0172] The controller 1110 may include at least one of a microprocessor, a
digital signal processor, a microcontroller, or logic elements capable of
performing similar functions to those of the above elements. The I/O
device 1120 may include a keypad, a keyboard, and a display device. The
memory device 1130 may store data and/or commands. The interface 1140 may
transmit data to a communication network or receive data from the
communication network. The interface 1140 can transmit data over a wire
or wirelessly. For example, the interface 1140 may be an antenna or a
wireless transceiver. The electronic system 1100 may further include a
high-speed DRAM and/or a high-speed SRAM as an operation memory for
improving the operation of the controller 1110. A fin field effect
transistor according to embodiments of the present inventive concept may
be provided within the memory device 1130 or provided as a part of the
controller 1110 or the I/O device 1120.

[0173] The electronic system 1100 can be applied to a personal digital
assistant (PDA), a portable computer, a web tablet, a wireless phone, a
mobile phone, a digital music player, a memory card, and all electronic
products that can transmit and/or receive information wirelessly.

[0174] FIGS. 37 and 38 are example semiconductor systems to which
semiconductor devices according to some embodiments of the present
inventive concept can be applied. FIG. 37 shows a tablet PC, and FIG. 38
shows a notebook computer. At least one of the above-described
semiconductor devices according to the embodiments of the present
inventive concept can be used in a Tablet PC, a notebook computer, and
the like. The semiconductor devices according to the embodiments of the
present inventive concept are applicable to other integrated circuit
devices not shown in the drawings.

[0175] In concluding the detailed description, those skilled in the art
will appreciate that many variations and modifications can be made to the
embodiments without substantially departing from the principles of the
present invention. Therefore, the disclosed embodiments of the invention
are used in a generic and descriptive sense only and not for purposes of
limitation.